Bioengineered Bugs Stir Dreams Of Scientists: Will they fly?
By Scott Kilman
Staff Reporter of The Wall Street Journal
January 26, 2001
PHOENIX -- Think genetically modified crops are controversial? Get a load of what they're doing to bugs.
Inside a gray cinder-block building in an industrial park here, amid manufacturers of auto parts and office furniture, a security camera watches as Robert Staten unlocks the door to a gleaming, windowless room. Its ventilation ducts are covered by fine mesh. "Here are the monsters," Dr. Staten jokes, peering into a paper carton the size of a quart ice-cream container.
It holds hundreds of wiggling pink bollworm moths, gene-spliced versions of a pest that sometimes decimates cotton fields in the Southwest. Dr. Staten's plan: engineer a male moth that can pass a fatal flaw on to any egg it fertilizes. Then fly over cotton country and drop millions of these modified males, enough to crowd out wild males in the quest for mates. Result: a lot fewer bollworm babies next season.
His is just one of many plans in the works to create what might be called biobugs. Some scientists hope to give beneficial insects such as honeybees immunity to diseases and pesticides. Others see a way to attack harmful insects without chemicals. Some researchers are genetically engineering the microbes that live inside insects.
Biobugs could fight diseases that annually kill or maim millions of the world's poorest people. Several teams are modifying insects so they can no longer transmit the parasites behind malaria, dengue fever and Chagas' disease. Europe has issued a patent on the idea of using a modified mosquito to deliver a vaccine every time it bites someone -- a kind of flying syringe. "Transgenic insects have the potential for making a big difference to human health," says Kathryn Aultman, a National Institutes of Health program officer.
But there are many unknowns. The chief risks stem from the fact that these biobugs, to do their job, would have to be released into the wild. That's a critical difference between them and the genetically modified, but caged, fruit flies that scientists have long used like laboratory rats. Once released, the modified insects would be impossible to recall in case of unexpected consequences -- such as somehow triggering a change that turns a pest into a superbug. Moreover, since some biobugs would bite people, tests involving them raise tricky issues of informed consent.
Dr. Staten hasn't had to face such questions yet, because he has done his experiments indoors. So far, the bugs he is working with have been changed only to add a jellyfish gene that turns its hosts fluorescent when seen under a special microscope. But this summer, Dr. Staten wants to move his fluorescent charges to a giant cage in a cotton field, to make sure the genetic tinkering doesn't cause some unanticipated behavioral change. Scientists and regulators believe this would be the first time a genetically modified insect was studied outdoors, at least in the U.S.
Dr. Staten, who directs the U.S. Department of Agriculture's Animal and Plant Health Inspection Service laboratory in Phoenix, expects the moths to act normally, but he isn't taking any chances. Besides being caged, they would have their wings plucked. "I don't want to be the guy who releases the Frankenbug," he says.
He needs permission from the USDA, and it plans to publish a notice in the next few months soliciting public comment. Dr. Staten expects an uproar. The request is sure to grab the attention of antibiotechnology groups, which so far have focused mostly on genetically modified food -- the most zealous among them vandalizing university test plots.
The request may also force the government to focus on some issues it hasn't much considered so far. At this point, the USDA isn't even sure what geneticists would need to do to prove the environmental safety of taking biobugs outdoors. "We need to be very careful because there is more that we don't know about gene transfer than we do know," says Marjorie Hoy, a University of Florida entomologist and member of a USDA committee on biotechnology. She worries that not all genetic tinkerers are trained to think broadly about how their inventions might change the natural order of things. Often, "we're the sort who doesn't think much beyond the lab," she frets.
The USDA's focus is insects that bother crops and livestock. Who would police biobugs that bite people is unclear. The Environmental Protection Agency and the Food and Drug Administration, though involved in regulating crop genetics, lack either the authority or any great interest in regulating genetically modified insects. Biologist David O'Brochta approached the Centers for Disease Control and Prevention when he wanted to transport the eggs of genetically modified mosquitoes, since they were the kind that can carry yellow fever. But because these eggs weren't actually carrying the disease, he says, the CDC didn't claim jurisdiction, either. At the CDC, "we haven't really thought much about" regulating genetically modified insects, says Jonathan Richmond, director of the Office of Health and Safety.
So Dr. O'Brochta fended for himself, fashioning an escape-proof package out of a screw-top polypropylene tube, inside an aluminum receptacle, inside a fiberboard mailing case. In that, they went by Federal Express from California to his lab at the University of Maryland. He worries that others might not be so conscientious about packaging. "It's time for the federal government to give us guidance," he says, "but no agency is willing to claim authority."
The medical establishment also has some biobug decisions to make. It's standard procedure that people who are subjects of clinical research must give their consent. What about people who may be bitten by future biobugs?
The kissing bug could be the first to confront that issue.
The long-nosed black bug, Rhodnius prolixus, hides in the crevices of dwellings in Latin America and at night bites occupants around their mouths, earning its nickname. Its bite can lead to Chagas' disease, which can scar heart tissue. Chagas' disease kills 50,000 people a year.
Charles Beard of the CDC believes he may have a solution -- not by modifying the bug per se but what's inside it. The kissing bug transmits disease through protozoa in its digestive system. Dr. Beard and a Yale doctor, Ravi Durvasula, have devised a way to make the kissing bug's insides an inhospitable place for these tiny parasites. They have taken bacteria that commonly live inside kissing bugs, then spliced in a moth gene so the bacteria produce a substance that kills the Chagas protozoa.
Now, how to get the modified bacteria inside the kissing bug? The curious appetites of baby kissing bugs provide a way. Born in the crevices of homes made of adobe and thatch, they dine on the dung of their parents. Drs. Beard and Durvasula invented a black paste that looks just like this delicacy but is laced with genetically modified bacteria.
To test it, they have built a Guatemalan-style hut inside a tightly sealed greenhouse on the CDC campus in Atlanta. In March they hope to release kissing bugs into the hut to see whether the paste gets the genetically modified bacteria inside them. Next year could come open-air field trials in Guatemala, where the CDC has a research station.
Would they need the permission of every villager the kissing bugs might bite? Every passerby? Dr. Beard plans to ask Guatemalan officials to excuse him from such a daunting requirement. He also would make sure that Guatemalan scientists were in charge of any field trials. "I don't want a backlash like there's been with crop biotechnology in some places," he says.
In a key respect, bug biotech differs from the crop genetics: the near-absence of corporations, which apparently don't see much profit potential in the insects. Most of the insect work is done by university and government scientists, funded by a few federal agencies, foundations and farm groups.
Even on tight budgets, they have made some notable gains, among them figuring out how to use a weird piece of genetic material called a transposable element to carry foreign genes into insects. U.S. geneticist Barbara McClintock discovered these elements in the 1940s. She identified bits of DNA that could insert themselves repeatedly into different chromosomes. Dr. McClintock, later honored with a Nobel Prize, worked with corn. Three decades later, other scientists discovered a transposable element in an insect, a fruit fly. Researchers soon hit on the idea of using the fly's transposable element to bring in a foreign gene and see what it did.
The fast-reproducing fly became an experimental workhorse, receiving gene transplants from all sorts of species, while never leaving the laboratory. In 1995, Notre Dame scientist Malcolm J. Fraser found a transposable element that could be inserted in many different insect species. This and the discovery of other such elements set off a stampede of entomologists into biotechnology.
There's a worrisome element here, though. Some scientists think that transposable elements, nicknamed "jumping genes," can on rare occasions leap from one species to another. What would happen, they ask, if a gene implanted to give honeybees protection from an insecticide somehow landed in a crop pest? "A lot has changed quickly," says Dr. Fraser. "The scientific community needs to recognize that we have to do something to regulate these things."
The most controversial biobug is one being designed in Julian Crampton's lab at the University of Liverpool in England. He is trying to modify a mosquito so it could deliver vaccine to people and livestock when it bit. In tropical regions, such an insect could potentially safeguard millions of poor people, out of reach of traditional medicine, from scourges such as polio and measles. "This is a way to vaccinate children who simply won't be vaccinated otherwise," Dr. Crampton says. A partnership called Insecta Ltd. is raising money for his work, and the European Union has granted him a patent on his idea.
A few months ago, Dr. Crampton created the prototype of a mosquito whose spittle contains a tiny bit of the protein cover that encases the malaria parasite. If it bites a mouse, the mouse would receive just enough of the protein to prompt its immune system to make antibodies. Then when another mosquito, one carrying the malaria parasite, sucked blood from this mouse, this insect would take up the antibodies. In its gut, they would attack the malaria parasites.
This is just a preliminary model in Dr. Crampton's program to develop a flying syringe. Many refinements are needed before he could ever use an insect to deliver vaccines to people. But already some scientists have concerns, among them: If people were bitten by numerous mosquitoes, each carrying a vaccine, might they get too big a dose?
See No Weevil
In Phoenix, Dr. Staten's ambitions are a bit narrower. He just wants biotechnology to give him a breakthrough in his three-decade battle with the cotton-loving pink bollworm.
The bollworm -- the larval form of a moth -- hides inside the cotton boll, out of the reach of chemical sprays. Although farmers are starting to raise cotton plants that are genetically modified to make a natural insecticide inside the boll, some still lose part of their crop to the insect.
Dr. Staten has managed to keep the pest from establishing itself in California's cotton-rich San Joaquin Valley. The USDA lab he oversees manufactures an army of sterile moths. Each morning, five million are packed into canisters, flown to Bakersfield, Calif., and then dropped from the air wherever a stray pink bollworm has stumbled into one of thousands of traps. The many sterile males prevent any fertile couples from finding each other. Releasing these bugs isn't controversial because they haven't been genetically modified, just sterilized.
In places where the pest is entrenched, such as Arizona and California's Palo Verde Valley, these methods wouldn't work. The means of sterilizing Dr. Staten's moths -- a blast of gamma rays -- renders them weaker and less competitive in the mating game, so they stand little chance against a horde of wild males.
To take territory away from the pink bollworm, a team led by Dr. Staten began trying five years ago to engineer a male moth that would be just as vigorous as a regular one in mating but pass a deadly genetic flaw to its progeny. With such a biobug in mass production, Dr. Staten figures he could eradicate the pink bollworm in the U.S., to which it isn't native.
The trick is creating a breeding population of moths that wouldn't be killed by the very flaw they are supposed to pass on. Collaborating with Dr. Staten is a team of scientists at the University of California in Riverside. They're working on a gene that would be dormant as long as the moths were in the lab and on a special diet, but become active once they were released. Activated, the gene then would produce a substance that disrupts cell specialization. An egg injected with this gene couldn't grow into an insect. The scientists at Riverside are beginning to transplant the gene into pink bollworms now, and hope to ship some soon to Phoenix for Dr. Staten to study.
The UC-Riverside scientists have done all this with skimpy funding, just $1 million from a trade group of California cotton farmers. One reason they can operate on such a slim budget, though, is that they aren't burdened by elaborate safety precautions such as those at Dr. Staten's USDA facility -- double sets of locked doors, bug-disorienting lights in hallways and a policy of freezing all trash lest a live bug be inside it.
"It would cost us 10 times as much to do" what Dr. Staten does on lab security, says UC-Riverside entomologist Thomas A. Miller, who at age 61 is so frugal he rides a motorcycle to work because it is cheaper than a car. His security system basically consists of a padlock on the door of the old walk-in incubator in which he keeps his genetically modified insects.
A 16-year-old laboratory assistant, who earns about $9 an hour, does much of the work involved with genetically modifying the pink bollworm. "When I think about what we're doing, it blows my mind," says the teenager, Luke Robertson, as he uses high-tech equipment to inject the lethal gene into moth eggs. Dr. Miller sees no problem. "There is absolutely no risk to him or the environment," he says.
In Phoenix, Dr. Staten isn't quite so sanguine. He figures that so much more remains to be learned about genetic engineering that nobody can make any guarantees now about what a biobug might do. It will still be a couple of years before a booby-trapped pink bollworm is ready for test release in the wild. And even if everything goes as he expects, Dr. Staten says, biobugs won't fly unless the public accepts some measure of uncertainty about them.
"The conundrum here is that I cannot prove zero risk," he says. But to him, "there is also a risk from not doing something new. There may be problems we can solve only with biotechnology."
A Swarm of Biobugs on the Horizon
Some of the projects to genetically modify insects
||Progress So Far
||The Big Hurdle
|Mosquito (Aedes aegypti)
||Replace disease-carriers with breeds resistant to malaria and dengue-fever parasites.
||Alexander Raikhel of Michigan State rewired it to produce antimicrobial defensin. Anthony James of University of California, Irvine, is trying to get it to make anti-bird-malaria antibodies.
||Figuring out how to drive disease-fighting genes into wild strains.
|Medfly (Ceratitis capitata)
||Use gene warfare to prevent this agricultural pest from infesting the U.S.
||Alfred Handler of USDA has spliced in the jellyfish gene marker and is trying to express a sperm-killing gene in the Medfly's testes. Some efforts underway in Greece.
||Making biobugs that aren't killed by the fatal trait they're supposed to pass along to offspring.
|Kissing Bug (Rhodnius prolixus)
||Replace with a version incapable of spreading Chagas' disease.
||CDC and Yale have caused bacteria in its gut to make substance that kills the disease's protozoa. Slated for testing in a greenhouse in March.
||Settling whether it is safe and ethical to release biobugs that bite people.
|Honey Bee (Apis mellifera)
||Protect this struggling bug, vital for pollinating many crops, from diseases and pests.
||Research at very early stages in the U.S., Japan and Europe. Ohio State researchers have attached jellyfish gene to bee sperm and it was inherited by offspring.
||Learning how to integrate foreign genes into bee chromosomes.
|Silkworm (Bombyx mori)
||Increase its silk output and modify for making medically important proteins.
||Researchers in Canada and Japan have successfully used different transposable elements in it.
||Find foreign genes for transplanting into the bug.
Sources: Insect Molecular Biology journal, Insect Transgenesis: Methods and Applications, and researchers.
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